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Thread: Unequally Disposed Profile

  1. #1

    Unequally Disposed Profile

    Good afternoon,

    I got a problem with the total tolerances of shape and location, and I wanted to ask for help in mastering one issue:

    We had received a drawing for processing the part and it shows the Profile of a Surface with unilateral tolerance to Datum "B" of the end of the detail . How to correctly interpret this meaning? Do I understand correct that a size of 129 mm from the center of the part - due to this “lead chamfer” can have a tolerance of 129 0/+1mm (129-118 = 11 0/+1mm)?
    Please find enclosed pictures
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  2. #2
    Technical Fellow Kelly_Bramble's Avatar
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    Datum B is derived from the two vertical surfaces associated with the 204 +/- 0.5 limits of size. From those two surfaces a center plane is establish regardless of feature size. I like to call this my “zero” location.

    The profile of a surface specification “circle U” specifies a unilateral tolerance of 1 from the as-shown, as-drawn location surface.

    That Circle “U” indicates that amount of unilateral tolerance to the outside of the as-drawn surface.

    Therefore, the location and size of the tolerance boundaries are 129 -0, +1 or minus zero plus 1.

    Had the specification been Circle U 0.3 the there would be a requirement of 0.3 to the outside of the as-drawn profile and 0.7 to the inside.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

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